1. Field of the Invention
The following description relates generally to a multiple-input multiple-output (MIMO) communication system. More particularly, the following description relates to a method of transmitting and receiving data using a codebook, and a transmitter and a receiver using the method.
2. Description of the Related Art
A multiple-input multiple-output (MIMO) communication system is an important technology used to achieve a high data rate and reliability in a wireless channel. When multiple users are simultaneously present, even higher data rates can be achieved thanks to the gain offered by multi-user diversity. In order to exploit the full benefit of multi-user diversity, however, the transmitter requires full channel knowledge. In a real system, it is unrealistic to feedback all channel information to the transmitter. Accordingly, the transmitter can only count on a limited amount of feedback. Therefore, in a multi-user channel environment, a design scheme in which a transmitter only uses partial channel knowledge is required.
According to a conventional development of multi-user diversity, user diversity cannot be sufficiently used when each transmit antenna is allocated to a different user.
Thus, in a multi-user MIMO communication system, limited feedback information and multi-user diversity must be simultaneously considered to design a codebook. A codebook is a transmission precoding technology consisting of a set of transmission precoding matrices. The transmitter uses one of those pre-defined matrices to transmit data streams based on the information feedback by all users. In addition, when the codebook is designed, the codebook must be systematically linked to propagation conditions, and simultaneously, a sufficient distance between the matrices must be maintained.
In addition, performance is improved if the codebook can be adapted as a function of the propagation conditions. Naturally, a sufficient distance between matrices must be maintained in order to maximize performance.